Design And Implementation Of Plug-in Cloud Desktop Protocol Server

As a typical representative in the field of cloud computing,cloud desktop can deliver traditional computer desktops or a single application to remote terminals through virtualization technology,so that users can access the desktop remotely through applications or thin clients,thus getting rid of time and place constraints.At present,there are many kinds of cloud desktop protocols with their own advantages and disadvantages.However,in the face of users' changeable usage scenarios,it is difficult to meet users' requirements simply by using a cloud desktop protocol.In addition,most cloud desktop protocols require users to download client applications.However,client applications are often limited by operating systems and cannot be used across platforms.Therefore,this thesis designs a cloud desktop protocol called PCDP based on web browser,and focuses on the implementation and optimization of the protocol on the server side.The server provides dynamic plug-in support for the current mainstream cloud desktop protocols,enabling transparent transmission of protocols.At the same time,the server can be combined with the existing QEMU-KVM private cloud platform of the laboratory to improve the convenience of users using virtual machines in the cloud platform environment and meet user requirements in different scenarios.Aiming at the compatibility between cloud desktop protocol client and operating system,and considering the high popularity and platform independence of web browser,this thesis designs a cloud desktop protocol called PCDP which is easy to transmit and understand based on web browser,and designs a model architecture of PCDP proxy service based on the protocol,which can convert and process data between the user and the target server,that is,realize the conversion between the PCDP protocol and the underlying protocol,however,this conversion is completely transparent to users.Aiming at users' changeable usage scenarios,this thesis uses dynamic linking technology,which allows users to load the underlying protocol plug-ins that are most suitable for the current scenario on demand.Meanwhile,it also allows developers to write plug-ins of specified protocols.At present,this thesis designs and develops plug-ins related to three underlying protocols: SSH,VNC and SPICE.They all realize the basic response to mouse and keyboard events,cut and copy operation in local environment and cloud environment,and expand the encryption upload and download function of files based on SFTP protocol.Aiming at the problem that data transmission occupies too much bandwidth,this thesis combines server rendering with client rendering to give full play to their performance.The server is responsible for completing complex image processing,while the client is only responsible for simple operations such as layer copy,layer deletion and layer movement,these operations are issued by the server through drawing instructions.In addition,this thesis also reduces the transmitted image data by deleting unchanged pixels,merging refresh,delay refresh,image compression and other ways to reduce the network bandwidth.Finally,the cloud desktop protocol server implemented in this thesis is deployed to the existing QEMU-KVM private cloud platform of the laboratory for functional test,comparison test and stress test.The test results show that the functions of the system meet the expected design and can meet the needs of a certain number of users in the cloud desktop environment.